Familial aggregation of blood pressure and heart rate responses during behavioral stress

Parent-offspring and sibling resemblances in blood pressure and heart rate responses to behavioral stress were evaluated in a sample of 142 families residing in an upper-middle-class community in the Pittsburgh metropolitan area between 1983 and 1985. The sample consisted of 121 daughters and 96 sons ranging in age from 7 to 18 years, and 141 mothers and 119 fathers ranging in age from 31 to 62 years. Three stressors were presented to all participants: serial subtraction, mirror image tracing, and isometric handgrip exercise. Multivariate analyses of the stress responses were based on maximum likelihood estimations of the magnitude of association, which provided collective significance tests, and were adjusted for familial resemblance of resting pressure and heart rate as well as body mass index. These analyses showed significant parent-offspring and sibling associations in resting blood pressure and body mass index, which replicate those found in previous epidemiological investigations. The novel findings in this study were the sibling similarities in heart rate responses to mirror image tracing and in systolic blood pressure responses to isometric handgrip exercise. An analysis of a subset of the sample--only those nonmedicated parents compliant with instructions not to smoke or drink caffeinated or alcoholic beverages for 3 hr prior to testing and their children--showed a parent-offspring resemblance in systolic blood pressure responses to isometric exercise. This analysis, along with the significant sibling association from the full sample, suggests that systolic blood pressure responses to static exercise might aggregate in the family. The results are discussed in light of previous twin data. The relative paucity of significant parent-offspring associations of physiological parameters during serial subtraction and mirror image tracing tasks implies that non-familial influences are most important in determining cardiovascular responses to psychological stress.